Safety guard for punch presses



April 1, 1941. J. M BLANE SAFETY GUARD FOR PUNCH PRESSES 1NVENTOR. James/72620316100 ATTORNEY.

the motion of the guard prevents the lPatented Apr. 1', 1941 UNITED STATES PATENT. jO FFlCE' SAFETY GUARD Foa PUNCH rasssns Application January is, 1940, Serial No. 314,135

5 The present invention relates to a safety guard for punch presses and the like and more parpreferably in the form shown in applicant's co-.

ticularly to' an interlocked guard and trip-actuv atin'g device for preventing iniury to an operator.

It is common to use mechanically operated gates or movable guards for insuring that the hands of a punch press operator arein positions of safety when the press is operated. Such devices, however, are not usually favored by the operator since they slow down the operation of the press and, as usually constructed, they op-' erate to forcefully and without control by the operator.

It is an object'of the presentinvention to-pro-' vide a novel control mechanism for presses-and the like .having a guard member interlocked therewith in such manner that obstruction of tripping oi the operating clutch. I a

It is another object to provide such a device incorporating an electrical tripping means for the operating clutch.

It is a further object to provide such a device in which a control treadle actuated by the operator first lowersthe guard member and then closes a switch which causes actuation of the electrical clutch-tripping means.

It is another object to provide such a device incorporating a yielding connection between the guard member andtreadle to prevent closure of the control switch by manipulation of the guard member.

Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawing which illustrates in perspective a punch press incor- The single stroke mechanism illustrated is pendingapplication Serial Number 298,284, filed October 6, 1939, and since this mechanism forms no part of the present invention, it is deemed .unnecessary to describe it further than to state that a'solenoidin the casing I6 is energized by current from the feed line I! under the control of a switch It, the arrangemehtbeing such that closure of theswitch ll causes the clutch to be tripped and released so as, to cause one revolution' of the operating shaft 4,- afterwhich further actuation can be secured only by opening the switch i8 and again reclosing it.

The switch It is adapted to be operated through. a link l9 by a treadle 2|, the operating connection including a, crosshead 22 adjustably fixed in any suitable way tothe link It and to a switch operating rod 23. Suitable means-such v asa spring 2| is provided for normally maintaining the treadle in switch-open position.

. According to the, present invention, a guard member 25 is pivoted as indicated at 28 to the anvil block 2, and is'connected to be operated by the treadle 2| so that depression of the treadle brings the guard into such position as to prevent access by the operator to dangerous proximity to the ram! and the tool 8 carried thereby. For this purpose, the link I! is extended up-- wardly through a pivot 'stud 21 mounted on the uard 25, and a collar 28 is suitably fixedon the link above the stud so as to provide a positive tractive connection between the link and move it into operative position prior to closure porating a preferred embodiment of the present invention.

In'the drawing a punch press of conventional type is illustrated comprising a pedestal i supporting an anvil block 2 and providing a bearing 3 for an operating shaft I. Eccentric 5 on the end of shaft 4 is arranged to actuatea pitman 6 to reciprocate a ram .1 in guldeways l mounted on the pedestal. Ram I carries at itslower end a punching tool} which is arranged to cooperate with a die ll resting on the anvil block 2 to op-- erate onthe work.

Means for rotating the pperating shaft 4 is provided in the form of a constantly rotating pulley 'wheel l2 adapted to be connected-to the shaft 4 by nieans of a clutch l2 which'is arranged to be tripped so as to render it effective by means of a link It operated, by a single stroke mechanism II.

ofthe switch I 8. It will be understood that if the movement ofthe guard 25 to operative position is obstructed in any way as by interposition of the arm of the operator, it will be impossible I for the switch to close.

Yielding means are provided for returning the uardto idle position in the form of a compression spring '2! on link. It hearing at its upper end against the stud 21 and at its lower end against a thrust collar ll suitably fixed to the linkll. Spring is made weaker than spring 24 so that manipulation of the guard 25 to closed position is not e'flective to cause closure of the trip switch It. g In operation, starting with the. parts'in the positions illustrated. the operator places the work on the die II under the tool lot the ram and then removes. his hands and depressestreadle 2|. Guard 2851s thereby moved to operative easily and position and then switch ll closed to cause actuationoi' the clutch I! to connect the drive a wheel I! to the operating shaft 6. As soon as this connection has been made, it is possible for the operator to release'the treadie 2|, causing the guard 2| to rise, but since the motion of the press has by this time caused the tool to enter the work. it is impossible for the operator to become injured even though he should thrust his hands under the guard as soon as it rose suinciently to permit such action. The guard thus caused a minimum amount of interference with the operation.

It will be understood that the guard 23 may be made of light material, and since the pressure exerted thereon is simply the pressure exerted by the operator on the treadle II, it will be obvious that ii. the operator should inadvertently leave a hand or arm under the guard, the blow of the guard thereon will not be severe, and the pressure will be immediately relieved by the operator releasing the treadle 2|.

Since the force required to close the switch ll may be made quite small, the entire mechanism may be constructed of light and economical components, and the operation may be periormed rapidly without fatiguing the oper-" ator.

Although but one embodiment or the invention has been shown and described in detail, it will be understood that other embodiments are possible and various changes may be made in the design and arrangement oi the parts without departing from the spirit oi the invention as defined in the claims appended hereto.

What is claimed is:

1. In combination with a punch press or the like having an operating clutch, trip mechanism tor the clutch including a control switch, means ior closing the switch including a lever and link. and a movable guard for the press connected to said link and movable thereby into operative position prior to closure of the switch, said connecaasavso A v w mechanism as: the clutch including a control switch, means for closing the switch including a treadle and link. and a movable guard for the press connectedto said link and movable thereby into operative position prior to closure of the switch, .said connection including a lost motion connection and a spring take-up whereby moveor the switch. said connection including a sliding connection. ,a positive abutment for transmit- V ting motion from the link to the guard, and a take-up spring permitting movement of the guard to closed position without'moving the link to'closethetripswitch.

4. In combination with a punch press or the like having a reciprocating ram and a clutch for actuating the ram, an electrically operated single stroke control device for the clutch including a switch, means including a treadle for closing said switch, a safety guard movable into position to prevent access to the ram, and a positive connection from the treadle to the guard for moving the guard to-operativeposition prior to closure of the switch.

5. In combination with a punch press or th like having a reciprocating ram and a clutch tor actuating the rim, an electrically operated single stroke control device for the clutch including a switch, means including a treadle and link Ior closing said switch. a satetyiguard movable into position to prevent-access to the ram, a positive connection irom the link to the guard for moving the guard to operative position prior to cloticn being eiiectlve to prevent closure of the switch when movement of the guard. to operative position is obstructed.

2. In combination with a punch press or the like having an operating clutch, electrical trip sition. I 7

sure or the switch. and a spring connection between the link and guard for returning the guard to normal position, said spring connection being adapted to yield and prevent closure oi the switch by manipulation oi the guard to operative po- JAMES MACBLANE.' 

